Method of making ceramic dental restorations

Abstract

Dental restorations can be made by acquiring a three-dimensional digitized image of a dental restoration site. A ceramic blank from which volatile organic binders have been removed, is then machined according to the three-dimensional digitized image to form a “brown” ceramic restoration. This material is then sintered using microwave energy to provide a high density ceramic dental restoration corresponding to the dental restoration site. This method can be carried out within a few hours thereby saving the patient several dental visits and enabling the dentist to better serve the patient directly in the office.

1 . A method for making a dental restoration comprising: 
 A) acquiring a three-dimensional digitized image of a dental restoration site,    B) providing a “green” ceramic blank comprising zirconia and an organic binder and volatizing said organic binder to provide a “brown” ceramic blank comprising zirconia,    C) machining said “brown” ceramic blank according to said three-dimensional digitized image to form a corresponding “brown” ceramic restoration comprising zirconia, and    D) sintering said “brown” ceramic restoration using microwave energy to provide a ceramic dental restoration comprising zirconia,    wherein said organic binder is volatized from said “green” ceramic blank by heating in the range of from 400 to about 1000° C. for from about 60 to about 300 minutes.    
     
     
         2 . The method of  claim 1  wherein a data file of said three-dimensional digitized image is created.  
     
     
         3 . The method of  claim 2  wherein a predetermined enlargement factor is added to the linear dimension of said three-dimensional digitized image.  
     
     
         4 . The method of  claim 2  wherein said machining is carried out using a multi-axis CNC milling machine.  
     
     
         5 . The method of  claim 1  wherein a plurality of dental restorations are prepared simultaneously by carrying out steps A through D simultaneously using multiple three-dimensional digitized images and “green” dental blanks.  
     
     
         6 . (canceled)  
     
     
         7 . The method of  claim 1  wherein said “green” ceramic blank is a molded green ceramic blank that has been prepared by uniaxial dry pressing, cold isostatic pressing, slip casting, or injection molding a ceramic powder in the presence of one or more organic binders.  
     
     
         8 . The method of  claim 7  wherein said “green” ceramic blank comprises polyvinyl alcohol.  
     
     
         9 . The method of  claim 1  wherein said “brown” ceramic restoration is sintered using microwave energy at a frequency of from about 2 to about 20 GHz for from about 2 to about 10 minutes at peak temperature of from about 1400 to about 1600° C.  
     
     
         10 . The method of  claim 9  wherein the total sintering time including heating and cooling is from about 20 to about 60 minutes.  
     
     
         11 . The method of  claim 9  wherein the frequency of said microwave energy is from about 2.4 to about 2.6 GHz.  
     
     
         12 . (canceled)  
     
     
         13 . The method of  claim 1  wherein said “brown” ceramic restoration is sintered to provide a fully density ceramic dental restoration.  
     
     
         14 . A method for making one or more dental restorations comprising: 
 A′) acquiring three-dimensional digitized images of one or more dental restoration sites,    B′) creating a data file for each of said three-dimensional digitized images and adding a predetermined enlargement factor to the linear dimension of each of said three-dimensional digitized images,    C′) transferring said one or more data files to a multi-axis CNC milling machine,    D′) providing one or more “brown” ceramic blanks comprising zirconia from which organic binders have been volatized from one or more “green” ceramic blanks comprising zirconia, by heating in the range of from 400 to about 1000° C. for from about 60 to about 300 minutes,    E′) machining said one or more brown ceramic blanks to form one or more brown ceramic restorations comprising zirconia, and    F′) sintering said one or more brown ceramic restorations using microwave energy to provide one or more full-density ceramic dental restorations comprising zirconia.    
     
     
         15 . The method of  claim 14  wherein said one or more “green” ceramic blanks comprise zirconia and polyvinyl alcohol, and 
 said one or more “brown” ceramic restorations are sintered using microwave energy at a frequency of from about 2.4 to about 2.6 GHz for from about 2 to about 5 minutes at peak temperature of from about 1450 to about 1550° C.